For example, an automatic analyzer such as a biochemical automatic analyzer or an immunological automatic analyzer includes a sample dispensing device which automatically suctions a liquid sample from a sample container and discharges the liquid sample to a reaction container (hereinafter, referred to as dispensing).
The sample dispensing device includes a sample probe, a dispensing syringe connected thereto, and a mechanism for moving the sample probe to a predetermined position. The sample dispensing device is configured to repeatedly perform a dispensing operation in which a distal end of the sample probe is inserted into a sample, and the dispensing syringe is driven by a predetermined amount. In this manner, a predetermined amount of the sample is suctioned, then the sample probe is moved to the reaction container, and the suctioned sample is discharged.
Incidentally, in a laboratory test such as a specimen test, a blood cell, a serum, and plasma are frequently used as the sample. If these are left neglected for a long time from collection until the test, a solid material (hereinafter, referred to as a clot) such as a fibrin thrombus is generated in the sample. If the sample is loaded into the automatic analyzer as it is, the generated clot clogs the sample probe in some cases. If the clogging occurs in the sample probe as described above, a predetermined amount of the sample cannot be dispensed to the reaction container, and thus an accurate analysis result cannot be obtained. This results in greatly damaged analysis reliability in the automatic analyzer.
As means for solving this disadvantageous problem, many inventors have proposed those which detect the clogging of the sample probe based on pressure variations by disposing pressure sensor inside a dispensing flow route including the sample probe. According to PTL 1, a value obtained through the secondary differentiation of a pressure variation waveform is focused on, and the value is compared with a threshold value In this manner, abnormal suction can be detected without being influenced by the viscosity. In addition, PTL 2 adopts a configuration in which residual pressure remaining on a negative side is focused on, and the clogging is determined when the residual pressure is lower than the threshold value, after the suction operation is completed. Furthermore, PTL 3 discloses a technology which determines abnormality during sample dispensing, based on a comparison between an area value obtained by integrating an output of the pressure sensor and a predetermined reference value. In addition, PTL 4 discloses a configuration which includes detection means for detecting the clogging of a sampling nozzle, and in which a sample analysis operation is stopped when severe clogging occurs.